You mention that the pull is subtle. This might go away after driving for a while and the arc of the shoes wear to match the arc of the drums. I have experienced this very thing more than once with new brakes on these old trucks, Huck and Bendix. Once they wear in, you will want to adjust the brakes again by the book.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission